Messages in this thread Patch in this message | | | Date | Sat, 12 Mar 2016 05:02:56 -0900 | From | Kent Overstreet <> | Subject | Re: e827091cb1 "block: merge: get the 1st and last bvec via helpers" broken |
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Here's the output of the patch below:
generic/036 11s ...run fstests generic/036 at 2016-03-12 13:58:21 end 4096 0 ffffea0001d611c0 end2 1024 0 ffffea0001d611c0 len 1024 offset 0 page ffffea0001d611c0 KGDB: Waiting for remote debugger
Your code gives a biovec with bv_len of 4096, the old code gives a biovec with bv_len of 1024 (and then we dump every biovec, we see that the bio had only a single biovec that did indeed have bv_len == 1024).
bio_get_last_bvec() is broken, please revert your patch for v4.5.
diff --git a/block/blk-merge.c b/block/blk-merge.c index 261353166d..231aec4fa3 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -318,6 +318,34 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, bio_get_last_bvec(bio, &end_bv); bio_get_first_bvec(nxt, &nxt_bv); + { + struct bvec_iter iter; + struct bio_vec end2, bv; + + bio_for_each_segment(end2, bio, iter) + if (end2.bv_len == iter.bi_size) + break; + + if (end_bv.bv_len != end2.bv_len || + end_bv.bv_offset != end2.bv_offset || + end_bv.bv_page != end2.bv_page) { + printk(KERN_ERR "end %u %u %p end2 %u %u %p\n", + end_bv.bv_len, + end_bv.bv_offset, + end_bv.bv_page, + end2.bv_len, + end2.bv_offset, + end2.bv_page); + + bio_for_each_segment(bv, bio, iter) + printk(KERN_ERR "len %u offset %u page %p\n", + bv.bv_len, + bv.bv_offset, + bv.bv_page); + BUG(); + } + } + if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) return 0;
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